Numerical controller reestablishing machine coordinate value by using absolute position detector

Abstract

A numerical controller for controlling a machine receives an instruction to reestablish a machine coordinate value of a movable part of the machine and stops a servo motor driving the movable part. When the servo motor is stopped, the numerical controller acquires position information of a position detector provided to the servo motor. Then, the numerical controller updates the machine coordinate value of the movable part based on the position information, and further updates the absolute coordinate value of the movable part based on the updated machine coordinate value.

The invention claimed is: 
     
       1. A numerical controller for controlling a machine including a movable part driven by a servo motor having a position detector, the numerical controller comprising:
 an axis stop unit configured to output an instruction to stop the servo motor upon receiving an instruction to reestablish a machine coordinate value of the movable part; 
 a machine coordinate value updating unit configured to acquire, when the axis stop unit stops the servo motor, position information of the servo motor detected by the position detector and update, based on the acquired position information, the machine coordinate value of the movable part; and 
 an absolute coordinate value updating unit configured to update, based on the machine coordinate value updated by the machine coordinate value updating unit, an absolute coordinate value of the movable part, 
 wherein the servo motor is stopped until the absolute coordinate value of the movable part is updated. 
 
     
     
       2. The numerical controller according to  claim 1 , wherein the instruction to reestablish the machine coordinate value of the movable part is issued based on a signal operation to the numerical controller. 
     
     
       3. The numerical controller according to  claim 1 , wherein the position detector is an absolute position detector. 
     
     
       4. The numerical controller according to  claim 2 , wherein the position detector is an absolute position detector.